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UNITED STATES PATENT OEECE.

NORMAN WHEELER, OF BROOKLYN, NEW YORK.

IMPROVEMENT IN PACKING SLIDE-VALVESFOR STEAM-ENGINES.

Specification forming part of Letters Patent N o. 55,406, dated June 5, 1866.

To all whom t may concern:

Be it known that I, NORMAN W. WHEELER, of the city of Brooklyn, county of Kings, and State of New York, have invented a new and useful Method of Packing Slide-Valves, and I do hereby declare that the following is a full and exact description thereof, reference being had to the accompanying drawings, with letters of reference marked thereon, forming a part of this specification, in which- Figure l represents a longitudinal section of a steam-cylinder tted with piston-valves; Fig. 2, a cross section of the same, and Figs. 3 and 4 like sections of steam-cylinders fitted with half-pistons or D-valves, like letters of reference indicating the same or similar parts in the several figures.

Piston slide-valves have been considered by theorists the best valves known-for steam-engines, and it is presumed they would be so were it not for the difficulty of mechanically adjusting the packing-rings to vmeet the peculiar requirements of their functions.

In all examples that have come to my knowledge the packing-rings have been set or compressed against the sides of the valve-cylinder by springs or other means by a constant energy. Now, when the valve covers only a part of a port whichis taking steam, so much of the piston as is not covered by the surface of the valve-cylinder is pressed inward by the action of the steam, and if the springs be not so strong as to cause a great amount of friction the ring must yield to such pressure and allow steam to pass the valve into the exhaustchamber. This difficulty has instigated the trial in many partially-successful instances of methods of setting the rings by rigid mechanical arrangements, whereby the valves, while absolutely in use, were in effect solid and unyielding pistons or disks, and only adjustable while less hot than when in use, and not capable of accommodating themselves gradually to the gradual wear ofthe parts.

In the example before us a is the steam-cylinder; b b, the side pipes; c c, the exhaust- Way; d d, the valve-rod, e e, the piston-valves; ff, the 'packing-rings thereof; Mt', small ports leading from the exposed valve-faces into the space within the rings, jj, the live-steam passage; g, the valve-cylinder, which is seen in Figs. 3 and 4 as a semi-cylinder, Z l.

When the engine is in motion the valves ee have a reciprocating motion longitudinally with their axis over and across the ports b I), and when either valve is delivering steam to the engine,vas seen at right hand in Fig. l, steam passes into the corresponding port and presses the rings inward, or, in the example Figs. 3 and 4, presses the valves up against the semi-cylinder b b; but at the same time steam passes into the space inside the rings and neutralizes the aforesaid pressure.

When the exhaust takes place the valve is in such position (see the left in Fig. l) that the steam flows out of one of the ports it and relieves the internal pressure at the same time that the external pressure is relieved, so that if the valve-pistons be fitted with ring-springs or the rings iit the valve-cylinder by their own elasticity, in the same manner as is usual for l working-pistons, the rings will have, for all the time not requisite for the laps of the ports 01 z', the effective pressure only of the springs against the sides of the valve-cylinder, and will accommodate themselves to the varying expansions and wear of the valve-cylinders in 'a more perfect manner than analogous devices have hitherto been made to do.

In Figs. 3 and 4, the valves having a solid face and being backed with packing-rin gs, the rings are made in halves or such parts of a-circle that their ends may it fair upon the valveface, the semi-rings being riveted together near the ends, and the cuts distributed prop- -erly around the semicircle, and the balancingports z' z' opening on the valve-face, so that they perform the same function as before described for the full piston-valves.

Having described my invention, I will proceed to state what I consider new' and useful, and for which I desire to secure Letters Patent, viz:

The ports t' i, in combination with packingrings, or segments thereof, expanded by their own elasticity or by especial springs, substantially as and for the purposes described.

NORMAN W. WHEELER.

Witnesses:

F. G. PRINDLE, EDWIN G. SHoARDs. 

